<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        body {
            margin: 0;
            width: 100vw;
            height: 100vh;
            display: flex;
            align-items: center;
            justify-content: center;
        }
        .box {
            width: 400px;
            height: 400px;
            background: #03a9f4;
            display: grid;
            place-items: center;
        }
        .box-item {
            width: 200px;
            height: 200px;
            background: #0037ff;
        }
    </style>
</head>
<body>
<div class="box">
    <div class="box-item"></div>
</div>
</body>
</html>
